The catalytic property of zeolites is one of the more exploited for several type of reactions in the industrial field and the number of reactions catalysed by them has been extended. Moreover, new multicomponent polyfunctional catalysts with specific properties have been developed. The future applications of zeolite catalysts could target the synthesis of fuel from renewable biomass to increase the energy sources availability while decreasing CO2 emissions. The origin of the catalytic property of these materials resides in the presence of active acidic sites of two different nature, Brønsted and Lewis acid sites. In this proposal we intend to monitor the effect of pressure-induced hydration on four Ga-exchanged different zeolites topology (ferrierite, mordenite, ZSM-12 and L characterized by different Si/Al ratio) possessing both Bronsted and Lewis acidity. The water molecules that are the nearest neighbours of metal cation form the primary hydration sphere, protons of water molecules directly bonded to hydrated cations can form relatively strong hydrogen bonds and they are of acidic nature due to hydrolysis reaction. The acidity of the cations depends on its charge (oxidation number) and on the water-complex formed. These information can be obtained by a detailed EXAFS study at the Ga K-edge.
Pressure-induced hydration in acidic cation-exchanged zeolites: an Exafs study at Ga k edge
Annalisa Martucci
Primo
2019
Abstract
The catalytic property of zeolites is one of the more exploited for several type of reactions in the industrial field and the number of reactions catalysed by them has been extended. Moreover, new multicomponent polyfunctional catalysts with specific properties have been developed. The future applications of zeolite catalysts could target the synthesis of fuel from renewable biomass to increase the energy sources availability while decreasing CO2 emissions. The origin of the catalytic property of these materials resides in the presence of active acidic sites of two different nature, Brønsted and Lewis acid sites. In this proposal we intend to monitor the effect of pressure-induced hydration on four Ga-exchanged different zeolites topology (ferrierite, mordenite, ZSM-12 and L characterized by different Si/Al ratio) possessing both Bronsted and Lewis acidity. The water molecules that are the nearest neighbours of metal cation form the primary hydration sphere, protons of water molecules directly bonded to hydrated cations can form relatively strong hydrogen bonds and they are of acidic nature due to hydrolysis reaction. The acidity of the cations depends on its charge (oxidation number) and on the water-complex formed. These information can be obtained by a detailed EXAFS study at the Ga K-edge.I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
